Visitors holding capstan bars turn the capstan

A capstan is a vertical-

axle An axle or axletree is a central shaft for a rotation, rotating wheel and axle, wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In ...

d rotating machine developed for use on sailing ships to multiply the pulling

force In physics, a force is an influence that can cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitu ...

of sailors when hauling ropes, cables, and hawsers. The principle is similar to that of the windlass, which has a horizontal axle.

History

The word, connected with the

Old French Old French (, , ; ) was the language spoken in most of the northern half of France approximately between the late 8th

Early form

In its earliest form, the capstan consisted of a timber mounted vertically through a vessel's structure which was free to rotate. Levers, known as bars, were inserted through holes at the top of the timber and used to turn the capstan. A rope wrapped several turns around the drum was thus hauled upon. A rudimentary ratchet (device)">ratchet was provided to hold the tension. The ropes were always wound in a clockwise direction (seen from above).

Later form

Capstans evolved to consist of a wooden drum or barrel mounted on an iron axle. Two barrels on a common axle were used frequently to allow men on two decks to apply force to the bars. Later capstans were made entirely of iron, with gearing in the head providing a mechanical advantage when the bars were pushed counterclockwise. One form of capstan was connected by a shaft and gears to an anchor windlass on the deck below. On riverine vessels, the capstan was sometimes cranked by steam power. RustonProctorSteamCapstan1883

Capstan winches were also important on sailing trawlers (e.g. Brixham trawlers) as a means for fetching in the nets after the trawl. When they became available, steam powered capstan winches offered a great saving in effort. These used a compact combined steam engine and boiler below decks that drove the winch from below via a shaft. Ruston, Proctor and Company at the UK 1883 Fisheries Exhibition marketed an engine, boiler, shafts and capstan designed specifically for this task.

Messenger

As ships and their anchors grew in size, the anchor cable or chain would be too big to go around the capstan. Also, a wet cable or chain would be difficult to manage. A messenger would then be used as an intermediate device. This was a continuous loop of cable or chain which would go around the capstan. The main anchor cable or chain would then be attached to the messenger for hauling using some temporary connection such as ropes called nippers. These would be attached and detached as the anchor was pulled up onto the ship; ( weighed) thus allowing a continuous hoist of the anchor, without any need for stopping or surging..

Modern form

Modern capstans are powered electrically, hydraulically, pneumatically, or via an internal combustion engine. Typically, a gearbox is used which trades reduced speed, relative to the prime mover, for increased

torque In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. Wh ...

Similar machines

* In yachting terminology, a

winch A winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise adjust the tension (physics), tension of a rope or wire rope (also called "cable" or "wire cable"). In its simplest form, it consists of a Bobb ...

functions on the same principle as a capstan. However, in industrial applications, the term "winch" generally implies a machine which stores the rope on a drum. * Most cassette players and other

magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic ...

audio devices utilize a device called a capstan to draw the tape from the cassette or reel across the tape head. It functions similarly to, and was likely named for, the nautical device.

Use on land

Hydraulically powered capstans were sometimes used in railway goods yards for shunting, or shifting railcars short distances. One example was Broad Street goods station in

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

. The yard was on a deck above some warehouses, and the deck was not strong enough to carry a locomotive, so ropes and capstans were used instead.

Notes

References

EtymologyOnLine
{{Sailing ship elements Watercraft components Spanish inventions